eric@milo.UUCP (09/21/84)
I recently received information on a new product from System Industries that supports multiple machine access to their disks. They also claim to have Unix support for this. The name of the product is "SIMACS". The natural question is - has anyone tried this yet? We are looking at enlarging our installation (more machines) and the ability to share disks (and even the data on the disks) between machines sounds very good. But it seems to be an extremely new product, at least for the Unix world. If there are any responses (and enough interest), I'll post the results. -- eric ...!seismo!umcp-cs!aplvax!eric
kds@intelca.UUCP (Ken Shoemaker) (09/23/84)
We had this beastie on two of our VAXes about a year ago that I had the misfortune of working on. At the time, they didn't have unix support (not that it would have made much difference) so the machines were running VMS. There were a couple of problems, none the least of which I could attribute to our VMS crew not quite knowing how to configure the systems to which it was attached. However one of the really fundamental problems I'm not sure Unix can approach any better, and it was a real performance killer. Consider two machines having write access for a single disk. For normal files perhaps it wouldn't cause too many problems, but for directory files you could have some nasty problems. With the kernel running on a single machine it has just one place where disks are cached, but with two machines doing the same thing, it can get kinda funky. As a result (at least for the VMS machines) one machine would hit the other machine to dump out its disk buffers whenever it wanted to do anything, and semaphores were kept on the disk itself. Anyway, high performance it ain't. In addition to these problems, I would make sure that the unix support is available. They were promising this last year, but last I heard, it was still "vaporware" (not that I'm casting aspersions, but a word to the wise....) -- I've got one, two, three, four, five senses working overtime, trying to take this all in! Ken Shoemaker, Intel, Santa Clara, Ca. {pur-ee,hplabs,amd,scgvaxd,dual,idi,omsvax}!intelca!kds ---the above views are personal. They may not represent those of Intel.